1. Technical Field
The present invention relates to an analyzer for measuring a highly contaminating/infectious analysis object, and more particularly relates to an analyzer with a disposable sensor, and to a constitution and measurement method for providing high assay accuracy.
2. Description of the Prior Art
In the field of sensors, when the analysis object as a sample is a substance of biological origin, this is specifically referred to as biosensing, and analytical devices used for this are called biosensing devices.
Biosensing devices include those in which the molecular recognition ability of microbes, enzymes, antibodies, and other such biomaterials is utilized among the measurement factors of a sensor that recognizes an analysis object, and a biomaterial is used as a molecular identification element. Specifically, materials of biological origin are used to send out signals proportional to concentration and the like, and so forth. In particular, we have seen the practical application of biosensors that make use of the immune response of antibodies or enzyme reactions, and these biosensors are widely used in the medical field and in the food safety field. Qualitative and quantitative methods that have been developed span a wide range, including electrochemical analysis and optical analysis. Also, when a highly contaminating/infectious analysis object is to be measured with a small sensing device, a disposable sensor is usually used in which the sensor portion that comes into contact with the sample can be removed.
In particular, with analyzers in the medical field related to the health of humans, when disposable sensors are used to prevent secondary infection, because of the important role of such devices, they need to have high measurement accuracy. Accordingly, with biosensing devices in the medical field, various corrections are made to the measured values for the specific components in the analysis object in order to achieve higher measurement accuracy. For instance, there is temperature correction, correction of measurement error due to similar substances, correction of interfering substances, and so forth, and when the analysis object is blood, there is a special hematocrit value correction. In turn, optimization of a calibration line and a sensor by lot management, and the like probably fall under the heading of correction.
Temperature is an especially important factor since it affects all physical and chemical reactions. For example, in the measurement of a specific component in an analysis object, if the ambient measurement temperature is higher than a reference temperature for which a calibration line has been set (although this does not apply unconditionally), there will be acceleration at various analysis (reaction) stages, and the measurement result will probably be greater than the actual true value, and if the temperature is lower than the set reference, the reverse may be true.
One commonly adopted method for solving this problem is to provide an environmental temperature sensor within the measurement device, select the value thereof as the temperature of the reaction region, and subject the specimen concentration value to temperature correction. This method, however, just involves artificially using the environmental temperature as the ambient measurement temperature, so error will occur if there is deviation between the temperature of the measurement component (or more precisely, the measurement region) and the environmental temperature. Particularly with extremely small measurement devices that are held in the hand, a discrepancy from the actual environmental temperature tends to occur when the device is warmed by the body heat of the user at the stage of preparing to measure.
In view of this, there has been a need for a way to measure and correct the temperature of an analysis object measurement component to achieve more accurate temperature correction (see Patent Citations 1 and 2, for example).
For instance, in Patent Citation 1 (Japanese Patent No. 3,595,315), the constitutions shown in FIG. 13a, which is an exploded diagram of a sensor, and FIG. 13b, which illustrates a measurement device in which a sensor has been inserted, are discussed. A thermally conductive layer 824 is provided to part of the sensor, and the temperature of the measurement component is transferred to the end of the sensor inserted in the measurement device. The measurement device is equipped with a temperature sensor 832 that measures the temperature through direct contact with this thermally conductive layer, measures the amount of heat transferred, and subjects the measured specific component concentration information to temperature correction.
In Patent Citation 2 (International Laid-Open Patent Application 2003/062812 pamphlet), the constitution shown in FIG. 14, which is a cross section of the main components of a measurement device in which a sensor is inserted, is discussed. A thermally conductive layer 912B is provided to a sensor holder directly under the analysis object measurement component of the sensor, the measurement device is further equipped with a temperature sensor 912A that comes into direct contact with this layer, the transferred heat or the direct temperature of the sensor is measured, and the measured specific component concentration information is subjected to temperature correction.